1. Field of Invention
The present invention relates to a thin-film transistor and method for manufacturing the same. More particularly, the present invention relates to a short-channel thin-film transistor and method for manufacturing the same.
2. Description of Related Art
As the progress in semiconductor manufacturing technology, the manufacturing process of thin-film transistor (TFT) is becoming faster and simpler. Accordingly, the TFT is widely used in computer chips, mobile chips, and TFT liquid crystal display (TFT-LCD), etc. When the TFT is applied in a LCD, the TFT can serve as a switch, and the images displayed by pixels of the LCD is controlled by the on/off state of the switch. The TFT switching speed between on and off states has to be fast. The switching speed relates to the on-current (Ion) of the TFT, and the enhancement of the Ion increases the efficiency and the performance of the TFT. The Ion relates to the ratio of the channel width (W) and channel length (L). The larger the ratio of the channel width and channel length (W/L) is, the larger the Ion is. Therefore, shortening the channel length of the TFT facilitates the efficiency and the performance of the TFT.
However, the exposure machine applied in the process limits the current minimum line width and distance at about 3 μm, which is unable to be further shortened. The margin for increasing the Ion of the TFT is therefore constrained, so as the efficiency and the performance of the TFT. How to make increase the efficiency and the performance of the TFT becomes an important issue.